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	Toxin Name ω-agatoxin-Aa3c (N-terminal fragment) Source Species Agelenopsis  aperta (Western grass spider) Toxin Group Agatoxin Description ω-AGTX-Aa3c is a member of a family of insecticidal and vertebrate-active toxins from Agelenopsis aperta that block a wide range of voltage-gated calcium (Cav) channels. The toxin has not been fully sequenced; the primary structure shown below is an N-terminal fragment. The prototypic family member ω-AGTX-Aa3a blocks calcium channels in insect central neurons but not at peripheral neuromuscular junctions. In vertebrates, it is broadly activity against all high-threshold Cav1 channels and Cav2 channels, but it is ineffective at blocking Cav3 (T-type) channels. Curiously, the block of Cav2 channels by this family of toxins is only partial even at saturating concentrations of toxin. It has been suggested that the toxins occlude inward current by acting as a partial plug or "leaky lid" in the outer region of the channel vestibule. The binding sites for the prototypic family member ω-AGTX-Aa3a and ω-AGTX-Aa4a on Cav2.1 (P/Q-type) channels are distinct and non-overlapping. The toxin is present in A. aperta venom at very low concentration (0-3 μM). Discovered 1993 This toxin last updated on Aug 20, 2010 Taxonomy Current Taxonomy Historic Taxonomy Kingdom Animalia Phylum Arthropoda Class Arachnida Order Araneae Infra-order Araneomorphae Family Agelenidae Genus Agelenopsis Species aperta Agelena aperta Agelenopsis aperta Agelenopsis aperta guttata Agelenopsis gertschi Biological Activity Neurotoxin Molecular Target ED50 IC50 Kd Pharmacophore Comment Calcium channel, voltage-gated (vertebrate): CaV1, non-specific Based on homology with ω-agatoxin-Aa3a and ω-agatoxin-Aa3b Calcium channel, voltage-gated (vertebrate): CaV2, non-specific Based on homology with ω-agatoxin-Aa3a and ω-agatoxin-Aa3b Calcium channel, voltage-gated (invertebrate) Based on homology with ω-agatoxin-Aa3a and ω-agatoxin-Aa3b Accessions Source Accession ArachnoServer AS000180 InterPro IPR005853 InterPro IPR013605 NCBI_Taxon 6908 Pfam PF08396 PIR E54252 PROSITE PS60023 UniProt P81745 Literature References Original Deposition References Ertel E.A., Warren V.A., Adams M.E., Griffin P.R., Cohen C.J., Smith M.M. Biochemistry 33:5098-5108 (1994) Type III omega-agatoxins: a family of probes for similar binding sites on L- and N-type calcium channels Other References Yan L., Adams M.E. J. Biol. Chem. 275:21309-21316 (2000) The spider toxin omega-Aga IIIA defines a high affinity site on neuronal high voltage-activated calcium channels McDonough S.I., Boland L.M., Mintz I.M., Bean B.P. J. Gen. Physiol. 119:313-328 (2002) Interactions among toxins that inhibit N-type and P-type calcium channels Protein Information Disulfide Bonds Left Residue Right Residue Evidence 2 19 Predicted 9 25 Predicted 27 38 Predicted Sequences Peptide Sequences >as:ω-agatoxin-Aa3c|sp:P81745 N-terminal fragment of toxin (Omega-Aga IIIC) from the venom of the spider Agelenopsis aperta that blocks Cav1 and Cav2 channels NCIDFGGDCDGEKDDCQCCXRNGYCSCYNLFGYLKRGCKXEVG Full BLAST BLAST mature toxin only Toxin Synonyms Synonym Type ω-agatoxin-Aa3c Recommended full name ω-AGTX-Aa3c Recommended abbreviation ω-agatoxin IIIC Synonym ω-Aga-IIIC Synonym (abbreviation)
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